Lift control systems



G. E. MINNS LIFT CONTROL SYSTEMS Filed March 15, 1967 5 Sheets-Sheet 1 SCI m DCL AER/7 DUL OUR/7 00R/2 Fla.

INV TOR GEQRBE ER\(L \NNS BY uwum xl ATTORNEYS July 9, 1968 5, MlNNs 3,391,759

LIFT CONTROL SYSTEMS Filed March 13, 1967 5 Sheets-Sheet 3 TLO Rl 10K R20 7K 10K" 7 8 22K I l R77 2K R54 47K c3 05 IO/lF W Fis. 2b

Qn nae iii? 35 ATTORNEYS July 9, 1968 Filed March 13, 1967 GEM LIFT CONTRO 5 Sheets-Sheet 4 MAM-0 R25 1K R27 10K R31 70K 10K R27 R24 R26 7K 70K TRQ TR4 R29 1 R23 E s 47K R28 22K J2 "Er 1F a TRQ 55 Ru2 R02 R59 ACRE '{J ,0 M- 000/2 FIG. 2c

GEOQGNQ EE'ZQRW BY QM ATTORNEYS July 9, 1968 G. E. MINNS 3,391,759

LIFT CONTROL SYSTEMS Filed March 15, 1967 5 Sheets-5heet 5 832, R37 1K R42 1K R33 08 R38 MN\M H 'vww-4| R34 R39 R43 0 47K 47K 7 K W5 W7 FIG. 2d

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ATTORNEYS United States Patent 3,391,759 LIFT CONTROL SYSTEMS George E. Minus, Hounslow, England, assignor to Dewhnrst & Partner Limited Filed Mar. 13, 1967, Ser. No. 622,524 Claims priority, application Gr/e6a6t Britain, Mar. 11, 1966,

9 8 Claims. (Cl. 187-52) ABSTRACT OF THE DISCLOSURE The invention relates to a control system for operating a lift door, having contactor relays operable one to open the door and another to close the door. A safety switch permits opening of the door only when the lift is stationary at a landing. A transistorized switching stage for opening and closing the door is set, while the lift is moving, to open the door so as to be immediately effective when the lift stops at a landing, and reset to close the door upon stopping of the lift at the landing. A delay circuit delays closure of the door after resetting of the transistor switch.

The invention relates to alift door control system comprising relays for controlling the door operating gear and a transistorised logic circuit for operating the relays. The logic circuit comprises a monostable flip-flop which normally keeps the doors closed. The flip-flop has three individual inputs forming on OR circuit to open the lift doors on occurrence of any one of a number of incidents.

The present invention relates to lift control systems and, more particularly, to control systems for operating lift doors.

According to the invention there is provided a control system for operating a lift door, comprising relay means operable to first and second states to move the lift door to open and closed positions respectively, first switch means operatively connected to the relay means to permit opera. tion thereof to said first state only when the lift is stationary at a landing, second switch means operatively connected to the relay means through said first switch means, said second switch means being operable to first and second states respectively to operate the relay means to said first and second states, and a circuit for operat ng said second switch means comprising a transistor switching stage operable to first and second states respectively when the lift is moving and stationary to operate said second switch means to said first and second states respectively, diode means connected between the transistor switching stage and the second switching means to render the second switching means substantially instantaneously responsive only to the output from the transistor switching stage in said first state, and a delay circuit connected to the output of the transistor switching stage and connected to said second switching means to operate said second switching means to said second state with a time delay after the transistor switching stage has switched to said second state.

The invention will be described by way of example with reference to the accompanying drawings, wherein:

FIGURE 1 is a diagram of a relay circuit for operating lift doors in accordance with the invention; and

FIGURES 2a-2d together form a diagram of a static switching circuit used in conjunction with the circuit of FIGURE 1 for operating the lift doors in accordance with the invention.

An A.C. supply is passed to terminal SC in FIGURE 1 at all times, except when a thermal relay (not shown) is operated due to overheating of the door moving apparatus.

The circuit of FIGURE 1 comprises a door closing contactor DCC and door opening contactor DOC which directly operate a motor (not shown) to close and open the lift doors (not shown) respectively. Contacts DCC/1 and DOC/ 1, in series with relays DOC and DCC respectively, are opened upon respective operation of relays DCC and DOC. Contacts DOR/1 and DOR/2 are opened and closed respectively by operation of a door opening relay DOR (FIGURE 21)). Contact ACR/1 is normally held closed by an operated auto-close relay (not shown herein, but described and illustrated as ACR in my co-pending application Serial No. 622,497, filed March 13, 1967), which is releasable for when the lift is required to park with doors open. Contacts DCL and DOL are limit switch contacts which are opened upon the lift doors becoming fully closed and fully opened respectively. Contacts OID are opened (by means not shown) whenever the lift is moving or is located (either moving or stationary) between landings, preventing operation of the door opening contactor DOC. More specifically, contacts OID are relay contacts. (the relay not being otherwise shown) operated whenever a main contactor (not shown) is operated to energise the main lift motor (also not shown). Contacts OID are also mechanically operated (opened) whenever the lift is located as aforesaid between landings.

Two A.C. outputs CL and OI are taken from the relay circuit of FIGURE 1 to the (predominantly static) switching circuit of FIGURE 2.

The circuit of FIGURES 2a and 2b comprises:

Static switching transistors TR1 to TRIO and TR9';

The relay DOR (a common emitter relay transistor stage (not shown) is connected between relay DOR and transistor TR7, producing a phase inversion so that relay DOR is operated when TR7 is cut off; this phase inversion is indicated by the double loop in the line to relay DOR);

Resistances R1 to R43, R50 to R59;

Capacitances C1 to C9;

Diodes D1 to D8.

The circuit also includes various contact sets as follows:

Contacts RU/1 and RD/l (FIGURE 2a) which are closed whenever the lift is in motion (running) up or down respectively;

Normally closed contacts DCC/2 (FIGURE 2a) operated by relay DCC (FIGURE 1);

Normally open contacts DOC/2 (FIGURE 2b) operated by relay DOC (FIGURE 1);

Normally open contacts SE (FIGURE 2b) forming a safety edge switch on the lift doors, to reopen them in the event of meeting with an obstruction;

Contacts ACR/2 (FIGURE 21)) which are normally held open by the operated auto-close relay (not shown) mentioned above.

The inputs to the circuit of FIGURE 2, in addition to the AC. inputs CL and OI mentioned above, comprise:

A negative feed at LO when a call for a particular landing is made, either from the lift itself or from a particular landing, when the lift is parked (doors closed) at the landing concerned, as described in my co-pending application Serial No. 622,529 entitled Lift Control Systerns;

A negative feed at QC, to close the lift doors immediately (quick close), when a car call is made.

Negative full-wave rectified unsmoothed supply voltage is supplied to terminal M, in a similar manner as to the corresponding terminals M in my co-pending applications Ser. No. 622,529 and Ser. No. 622,497.

It is believed the connections of the: elements will be sutficiently clear from the drawing not to require detailed description. i

Door drive,--The lift doors are operated by a DC door motor (not shown) fed from the main lift supply, with the motor field winding and an electromagnetic brake (not shown) connected in series across the same supply. Directional control is achieved by the door opening contact DOC and the door closing contactor DCC. Operation of either contactor DCC or DOC energises the motor armature in the correct direction, short-circuits the brake (by means not shown), cuts the operating circuit to the other contactor DOC, or DCC, by opening contact DOC/1 or DCC/1 respectively, and provides certain control signals for interlocks.

Thermal overload protection (not shown) is provided, operative by cutting the supply to the terminal SC. There are also door position latches (not shown) to insert slowing resistors (not shown) in the motor circuit as the doors near the end of their travel.

Control of the contactors DOC and DCC is by means of the door operate relay DOR and travel limit switches DCL and DOL.

. Switches DCL and DOL are closed unless the doors are fully closed or fully open, respectively. When contacts DOR/2 are operated (closed), they set up the circuit for contactor DOC and, if DOL is closed (doors not fully open), OID not operated (lift stationary), and DCC/1 closed (DCC not operated), DOC will be energised and the doors will be opened. Normally, when the car is moving, DOR is operated but OlD being operated prevents the doors from being opened. As soon as the lift stops, OID releases to energise the previously-set-up DOC circuit.

After a delay for passengers to enter and leave the car, DOR is released and sets up the DCC circuit. If the autoclose relay (not shown) is operated, and relay DOC is not, and if switch DCL is closed, relay DCC will be energised and the doors Will close. Door opening and closing are terminated by the relevant limit switches DOL and DCL being opened, deenergising relays DOC and DCC respectively.

An AC control signal is derived from this circuit on the line CL when ACR/l is closed (as is normal) and the doors are not shut completely (i.e. DCL not opened). This signal is fed to the corresponding terminal in FIG- URE 2a and is rectified and smoothed and fed as a negative DC. signal to the base of TRl.

Door controL-Relay DOR is energised (TR7 cut off) while the lift is moving, or on operation of the safety edge switch SE and also, if the lift is stationary at a landing, so that RU/l and RD/l are open, when a negative feed is applied to L by a call for that landing or when the auto-close relay (not shown) is released, as described in my co-pending application Ser. No. 622,497 entitled Lift Control Systems. Relay DOR is also energised to open the doors if neither R relay is operated or the doors are not shut, after DCC has been energised for a few seconds and has not released, the presumption being that something has stopped the doors closing as they should.

After the lift stops at a floor relay DOR, energised while it was moving, remains operated for a predetermined time to permit passengers to enter and leave the car. It then releases, allowing the doors to close automatically. A car call placed during this period cuts it short (by applying a negative feed to QC) and closes the doors immediately.

Relay DCR is controlled, through the above-mentioned relay transistor stage (not shown) from the monostable pair TR6 and TR7. The stable condition, determined by diode D8 is with TR7 conducting and TR6 cut off. DOR is then released. A negative signal on the base of TR6 will change it over and energise DOR.

This negative signal can be provided in a number of Ways, via R34, R33 or R32. These are dealt with in turn.

Energising of DOR via R34.--When the car is moving, OID is operated to put earth potential on OI and, after the (relatively rapid) decay of the negative potential on C7, the TR4 base goes slightly positive (from the M+ bias line via R56) and TR4 is cut off. The TR4 collector then can rise in potential toward the negative potential of M, and C8 charges to almost this voltage. At the same time, R34 transmits the rapid rise (negatively) of collector potential to the base of TR6 and DOR is energised. On the lift stopping, OID releases. This puts a negative potential from OI on the TR4 base and makes it conduct heavily, but diode D7 isolates TR4 from the succeeding circuit. C8 now holds the monostable pair unchanged (TR6 conducting) until its charge has decayed. At this time, the pair reverts to its stable state and DOR releases. If ACR/l is closed, as is normal, DCC is nOW energised and the doors close.

While the doors are opening, contacts DOC/2 ground the junction of R29 and R30. This ensures that TR4 is now completely out off and no extra current through R31 can delay the energising of DOR. This can also be achieved, in the same way, by the safety edge switch SE when the doors are closing.

The time delay provided by the discharge of C8 is variable (by means not shown). TRS acts as a variable impedance in parallel with C8, and its effective value governs the rate of discharge and hence the time for which the doors stay open before they automatically reclose. Control of TRS is by its bias potential, applied by means not shown.

Alternatively, the doors may be closed immediately, by making a car call, which causes a negative feed to be applied to terminal QC (by means not shown). This causes TRS to conduct hard and completely discharge C8. TR6 and 7 can therefore revert immediately to their stable state, DOR releases and the doors reclose.

Energising of DOR via R33.-A negative signal appears on R33 (to operate relay DOR) when TR9 is not conducting, by reason of a ground-potential signal on the base of TR9. This can only occur if the car is stationary (RU/2 and RD/2 closed) and either ACR/Z is closed (i.e. the auto-close relay is released because no autoclosing is required) or the doors are closed and a landing call where the lift is parked produces a negative feed at LO. ACR/Z closed puts M-supply onto R59 and thence onto the base TR9". If RU/2 and RD/2 are closed, the TR9 collector (and TR9 base) will be held at near ground potential and any signals on R22 and R24 are ineffective. Alternatively, if ACR/ 2 is open and TR9 therefore not conducting, both R22 and R24 must have ground potential on them for TR9 to be cut off. This means that terminal CL must be at ground potential (and hence output terminal D also), i.e. the doors must be shut, and TRS must be conducting. As was stated above, a call for a particular landing when the car is already at the landing concerned will apply a volts) negative pulse to L0. The leading edge of this pulse, shaped and applied to the base of T R8 will make it conduct heavily, so fulfilling the required condition for DOR to be energised.

Energising of DOR via R32.This feed is controlled by the monostable pair TR3 and TR10. The stable state of this pair, determined by diode D3, is with TR3 cut off and the negative potential at its collector fed through D4 and R32 to cause DOR to be energised. The pair is held in its unstable state by a negative signal at the base of TR3. This requires DCC to be released (DCC/2 closed) and TR2 to be cut off by the conduction of TR1 (the TRI base to be negative), due either to D being negative (by reason of the doors not being shut) or to the junction of R4 and R5 being negative (by reason of the lift being stationary so that RU/l and RD/l are both open). This, as stated, will keep TR3 base negative. It will also charge up C2, so that a charge on C2 is an indication that the lift has stopped or that the doors have been open, and that DCC has been released. As stated, this holds offv the pair TR3 and 10, and they do not tend to energise DOR.

If DCC is now energised to close the doors, only the charge on C2 holds the pair TR3 and TRIO in its unstable state. The capacitor C2 will discharge through TR3 with a time constant of about 5 seconds. When it has discharged sutficiently, the pair will revert to its stable state and DOR will be energised. If however, the doors have satisfactorily closed before this time and the lift travel started, the operation of contacts OID will prevent DOC being energised by DOR when it does operate.

Open interlock.When the car is in motion, so that contacts OID are open, the door opening contactor DOC cannot operate to open the doors.

What I claim is:

1. A control system for operating a lift door, comprising relay means operable to first and second states to move the lift door to open and closed positions respectively, first switch means operatively connected to the relay means to permit operation thereof to said first state only when the lift is stationary at a landing, second switch means operatively connected to the relay means through said first switch means, said second switch means being operable to first and second states respectively to operate the relay means to said first and second states, and a circuit for operating said second switch means comprising a transistor switching stage operable to first and second states respectively when the lift is moving and stationary to operate said second switch means to said first and second states respectively, diode means connected between the transistor switching stage and the second switching means to render the second switching means substantially instantaneously responsive only to the output from the transistor switching stage in said first state, and a delay circuit connected to the output of the transistor switching stage and connected to said second switching means to operate said second switching means to said second state with a time delay after the transistor switching stage has switched to said second state.

2. A control system according to claim 1, wherein the relay means comprises two lift door motor-operating relays, a first one to open the lift door and a second one to close the lift door, and said first switch means is connected in the operating circuit of the first relay.

3. A control system according to claim 1, wherein said second switch means comprises two transistors connected together to form a fiip-fiop circuit and a further relay ar ranged to be operated by the flip-flop circuit.

4. A control system according to claim 1, wherein said second switch means is monostable in said second state.

5. A control system according to claim 1, comprising a second transistor stage responsive to a call made within the lift to operate said second switch means substantially instantaneously to said second state.

6. A control system according to claim 5, wherein said second transistor stage forms part of the delay circuit and is adjustable to vary the delay.

7. A control system according to claim 1, wherein a further transistor stage is operative to switch said second switch means to said first state when the lift is stationary at any given landing with the lift door closed and a call for the lift is made at that landing, switch means rendering said further transistor stage unresponsive when the lift is moving and said further transistor stage being responsive to a signal voltage or potential produced by the call.

8. A control system according to claim 4, wherein a further monostable transistor stage is normally operative to switch said second switch means to said first state, the last-mentioned monostable transistor stage being operable to its unstable state by a signal voltage or potential produced by means responsive to the simultaneous two conditions of firstly the relay means not being operated to said second state and secondly the lift door not being shut and/ or the lift being stationary, a delay circuit being operative to delay restoration of the last-mentioned monostable transistor stage to its stable state after the relay means has been operated to said second condition.

References Cited UNITED STATES PATENTS 3,082,845 3/1963 Duncan 18752 3,285,369 11/1966 Hornung 18752 3,301,350 1/1967 Hallene l87--52 EVON C. BLUNK, Primary Examiner.

RICHARD E. AEGERTER, Examiner.

H. C. HORNSBY, Assistant Examiner. 

